2002 TJ 4.0L swap for my 1991 4.0 HO?

[Tazmatic]

I have a chance to buy a 4.0 with 14k miles from an 02 TJ that I'd like to drop in my 91.

 

Will it work?

 

What kind of problems should I expect?

 

Any input would be appreciated. :chillin:

 

Tim

[pingpong]

I would expect lots of problems, considering the wiring is totally different as well as computer issues. If you do this you will need the complete harness and comp, to see any real benefit

[89MJComanche]

I don't know why everyone makes this so difficult.

 

First of all, you absoloutly don't want the new wiring, computers etc. The only benifit is that the newer motors have no distributor, instead a coil pack, which if sealed properly, means that your motor would run in deeper water.

 

As for the newer motors, just use the long block, with head, intake manifold, and exhaust manifold.. I'd keep all the old wiring, and ignition, and all that other stuff.

 

My 1995 XJ with 265" tires and 355 gears (AX15 equipped) gets 19MPG and has tons and tons of power. That includes at least 500lbs of armor and extra weight. My 2005 LJ Rubicon with 265's and 4.10's, lacks power, gets horrible gas mileage, and is equipped nearly the same as the 1995 XJ.

 

Other newer Jeeps that I have owned and driven are exactly the same way. The older stuff, 1995, and 1999 in particular, are way better than any of the crapola they put on there for emissions in the past 7 years. Take the 1999 manifold, and put it on a 1995 engine, and you should have a real power house.

 

I do have a gale banks Torqe Tube on the 1995 and I wonder how much that affects it performance, but never the less the 2005 will be getting hopped up with exhaust and intake as soon as the Warranty runs out.

[Eagle]

Your 91 uses a temp sender in the thermostat housing for the ECU, and one in the back corner of the head for the gauges. The new engine will not have a hole in the head for the sender to feed the gauge, because the newest Jeep electronics feeds the gauge data from the central PCM data buss. The water passage is there -- just drill and tap the hole (carefully, keeping the metal chips out of the water passage).

[Tazmatic]

Thanks guys!

 

My reason for the swap in the 91 is an extremely loud knock and a leaky everything. I can buy the new engine for cheap.

 

My 88 at 142k is still strong and passed the smog test yesterday.

 

I've done tons of axle, tranny, and T-case swaps. We have lifted and repaired many jeeps in my garage. I can weld anything from a broken heart to the crack of dawn. Swapping an engine is a first for me.

 

Will the old heads and intake bolt up from 91 to 02? Would that be the easiest route?

 

Tim

[89MJComanche]

I am not 100% sure on the head bolt up between those 2 years. I know that 91-99 was the same.

 

Some one with first hand knowledge will have to tell you.

 

I'd say that it probably will work.